1. Field of the Invention
The present invention relates to an apparatus and a method for managing beacon messaging period of vehicular communication, and more particularly, to an apparatus and a method for adaptively managing beacon messaging period using packet delivery ratio (PDR) as measured.
2. Description of the Related Art
Advancement in the electronics and communications technologies have enabled development of vehicles from conventional means of transportation to vehicular communication system that can provide communication services such as real-time traffic information, digital map, movies or music. The vehicular Ad-hoc network (VANET) including the vehicular communication system requires network technology that is distinguished from the conventional mobile Ad-hoc network (MANET) to suit needs of vehicles, i.e., speed and mobility.
IEEE Wireless Access in Vehicular Environment (WAVE) has been proposed as the wireless communication specification to provide the services such as VANET. This includes IEEE 802.11p and IEEE1609 standards, and supports fast linking between on-board unit (OBU) mounted on a vehicle moving with maximum 160 km/h speed and a road-side unit (RSU) installed along the road, and up to 27 Mbps high-speed data transmission. The IEEE WAVE specification has been initially developed in the North American region, but active commercialization and standardization are currently under way also in Europe, Japan, etc. The specification is also researched and developed in South Korea, as this has been opted as a candidate technology for the project led by the Korean Ministry of Land, Transport, and Maritime Affairs.
Collecting real-time traffic information is important to ensure that the intelligent traffic system stably serves traffic information. In order to do so, a system is necessary, which can collect, in real-time, related information from the vehicles on the road and transmit the traffic status analyzed based on the collected information to the respective vehicles, in real-time. However, considering that numerous vehicles are on roads, the information collected from these vehicles can increase considerable traffic in the communication between the vehicles and RSU. Various communication systems have been thus developed to transmit information to the traffic information center without loss of data.
One of these efforts relates to increasing communication capacity by adaptively adjusting beacon messaging period according to the status of the vehicles on road. For example, by utilizing the fact that the speed of the vehicle decreases as the number of vehicles on certain road area increases, it has been suggested that the beacon messaging period is managed adaptively in response to the variations in the vehicle speed, or adaptively managing beacon messaging period by utilizing the vehicular density on road.
However, the above-mentioned suggestions have shortcoming. That is, the beacon messaging period is not adaptively managed, when the vehicles run with relatively low speed on a road that does not have high vehicular density, or when vehicular density is particularly high at a certain point of road, while the road itself does not have high vehicular density overall. Accordingly, a problem occurs as the beacon messaging period is inadvertently set to be shorter and causes traffic collision of the beacon messages.